| 摘要 |
PURPOSE: To obtain a chelating agent comprising a polyaspartic acid and a salt thereof produced by hydrolyzing an anhydrous polyaspartic acid with a specified structure, having excellent biodegradability and chelating ability, useful as a detergent additive, a dispersant or the like to be discharged into the environment. CONSTITUTION: This chelating agent comprises a polyaspartic acid which is produced by hydrolyzing an anhydrous polyaspartic acid having a ratio (amide hydrogen/methine hydrogen)×100 of 7.0 or less, preferably 6.0 or less, or more preferably 5.0 or less and/or its salt (preferably an alkali metal salt, particularly sodium salt or potassium salt). The anhydrous polyaspartic acid is a reaction product obtained by reacting maleic acid as a monomer with ammonia or can be obtained by reacting maleamic acid or an aspartic acid in the presence or absence of a solvent, and in the presence or absence of a catalyst.
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